/// CheapToScalarize - Return true if the value is cheaper to scalarize than it
/// is to leave as a vector operation.
static bool CheapToScalarize(Value *V, bool isConstant) {
- if (isa<ConstantAggregateZero>(V))
+ if (isa<ConstantAggregateZero>(V))
return true;
if (ConstantVector *C = dyn_cast<ConstantVector>(V)) {
if (isConstant) return true;
}
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return false;
-
+
// Insert element gets simplified to the inserted element or is deleted if
// this is constant idx extract element and its a constant idx insertelt.
if (I->getOpcode() == Instruction::InsertElement && isConstant &&
(CheapToScalarize(CI->getOperand(0), isConstant) ||
CheapToScalarize(CI->getOperand(1), isConstant)))
return true;
-
+
return false;
}
-/// Read and decode a shufflevector mask.
-///
-/// It turns undef elements into values that are larger than the number of
-/// elements in the input.
-static std::vector<unsigned> getShuffleMask(const ShuffleVectorInst *SVI) {
+/// getShuffleMask - Read and decode a shufflevector mask.
+/// Turn undef elements into negative values.
+static std::vector<int> getShuffleMask(const ShuffleVectorInst *SVI) {
unsigned NElts = SVI->getType()->getNumElements();
if (isa<ConstantAggregateZero>(SVI->getOperand(2)))
- return std::vector<unsigned>(NElts, 0);
+ return std::vector<int>(NElts, 0);
if (isa<UndefValue>(SVI->getOperand(2)))
- return std::vector<unsigned>(NElts, 2*NElts);
-
- std::vector<unsigned> Result;
+ return std::vector<int>(NElts, -1);
+
+ std::vector<int> Result;
const ConstantVector *CP = cast<ConstantVector>(SVI->getOperand(2));
for (User::const_op_iterator i = CP->op_begin(), e = CP->op_end(); i!=e; ++i)
if (isa<UndefValue>(*i))
- Result.push_back(NElts*2); // undef -> 8
+ Result.push_back(-1); // undef
else
Result.push_back(cast<ConstantInt>(*i)->getZExtValue());
return Result;
/// extracted from the vector.
static Value *FindScalarElement(Value *V, unsigned EltNo) {
assert(V->getType()->isVectorTy() && "Not looking at a vector?");
- const VectorType *PTy = cast<VectorType>(V->getType());
+ VectorType *PTy = cast<VectorType>(V->getType());
unsigned Width = PTy->getNumElements();
if (EltNo >= Width) // Out of range access.
return UndefValue::get(PTy->getElementType());
-
+
if (isa<UndefValue>(V))
return UndefValue::get(PTy->getElementType());
if (isa<ConstantAggregateZero>(V))
return Constant::getNullValue(PTy->getElementType());
if (ConstantVector *CP = dyn_cast<ConstantVector>(V))
return CP->getOperand(EltNo);
-
+
if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
// If this is an insert to a variable element, we don't know what it is.
- if (!isa<ConstantInt>(III->getOperand(2)))
+ if (!isa<ConstantInt>(III->getOperand(2)))
return 0;
unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
-
+
// If this is an insert to the element we are looking for, return the
// inserted value.
- if (EltNo == IIElt)
+ if (EltNo == IIElt)
return III->getOperand(1);
-
+
// Otherwise, the insertelement doesn't modify the value, recurse on its
// vector input.
return FindScalarElement(III->getOperand(0), EltNo);
}
-
+
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
unsigned LHSWidth =
- cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
- unsigned InEl = getShuffleMask(SVI)[EltNo];
- if (InEl < LHSWidth)
- return FindScalarElement(SVI->getOperand(0), InEl);
- else if (InEl < LHSWidth*2)
- return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
- else
+ cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+ int InEl = getShuffleMask(SVI)[EltNo];
+ if (InEl < 0)
return UndefValue::get(PTy->getElementType());
+ if (InEl < (int)LHSWidth)
+ return FindScalarElement(SVI->getOperand(0), InEl);
+ return FindScalarElement(SVI->getOperand(1), InEl - LHSWidth);
}
-
+
// Otherwise, we don't know.
return 0;
}
// If vector val is undef, replace extract with scalar undef.
if (isa<UndefValue>(EI.getOperand(0)))
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
-
+
// If vector val is constant 0, replace extract with scalar 0.
if (isa<ConstantAggregateZero>(EI.getOperand(0)))
return ReplaceInstUsesWith(EI, Constant::getNullValue(EI.getType()));
-
+
if (ConstantVector *C = dyn_cast<ConstantVector>(EI.getOperand(0))) {
// If vector val is constant with all elements the same, replace EI with
// that element. When the elements are not identical, we cannot replace yet
Constant *op0 = C->getOperand(0);
for (unsigned i = 1; i != C->getNumOperands(); ++i)
if (C->getOperand(i) != op0) {
- op0 = 0;
+ op0 = 0;
break;
}
if (op0)
return ReplaceInstUsesWith(EI, op0);
}
-
+
// If extracting a specified index from the vector, see if we can recursively
// find a previously computed scalar that was inserted into the vector.
if (ConstantInt *IdxC = dyn_cast<ConstantInt>(EI.getOperand(1))) {
unsigned IndexVal = IdxC->getZExtValue();
unsigned VectorWidth = EI.getVectorOperandType()->getNumElements();
-
+
// If this is extracting an invalid index, turn this into undef, to avoid
// crashing the code below.
if (IndexVal >= VectorWidth)
return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
-
+
// This instruction only demands the single element from the input vector.
// If the input vector has a single use, simplify it based on this use
// property.
if (EI.getOperand(0)->hasOneUse() && VectorWidth != 1) {
APInt UndefElts(VectorWidth, 0);
APInt DemandedMask(VectorWidth, 0);
- DemandedMask.set(IndexVal);
+ DemandedMask.setBit(IndexVal);
if (Value *V = SimplifyDemandedVectorElts(EI.getOperand(0),
DemandedMask, UndefElts)) {
EI.setOperand(0, V);
return &EI;
}
}
-
+
if (Value *Elt = FindScalarElement(EI.getOperand(0), IndexVal))
return ReplaceInstUsesWith(EI, Elt);
-
+
// If the this extractelement is directly using a bitcast from a vector of
// the same number of elements, see if we can find the source element from
// it. In this case, we will end up needing to bitcast the scalars.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(EI.getOperand(0))) {
- if (const VectorType *VT =
+ if (VectorType *VT =
dyn_cast<VectorType>(BCI->getOperand(0)->getType()))
if (VT->getNumElements() == VectorWidth)
if (Value *Elt = FindScalarElement(BCI->getOperand(0), IndexVal))
return new BitCastInst(Elt, EI.getType());
}
}
-
+
if (Instruction *I = dyn_cast<Instruction>(EI.getOperand(0))) {
// Push extractelement into predecessor operation if legal and
// profitable to do so
if (I->hasOneUse() &&
CheapToScalarize(BO, isa<ConstantInt>(EI.getOperand(1)))) {
Value *newEI0 =
- Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
- EI.getName()+".lhs");
+ Builder->CreateExtractElement(BO->getOperand(0), EI.getOperand(1),
+ EI.getName()+".lhs");
Value *newEI1 =
- Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
- EI.getName()+".rhs");
+ Builder->CreateExtractElement(BO->getOperand(1), EI.getOperand(1),
+ EI.getName()+".rhs");
return BinaryOperator::Create(BO->getOpcode(), newEI0, newEI1);
}
} else if (InsertElementInst *IE = dyn_cast<InsertElementInst>(I)) {
// If this is extracting an element from a shufflevector, figure out where
// it came from and extract from the appropriate input element instead.
if (ConstantInt *Elt = dyn_cast<ConstantInt>(EI.getOperand(1))) {
- unsigned SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
+ int SrcIdx = getShuffleMask(SVI)[Elt->getZExtValue()];
Value *Src;
unsigned LHSWidth =
- cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
-
- if (SrcIdx < LHSWidth)
+ cast<VectorType>(SVI->getOperand(0)->getType())->getNumElements();
+
+ if (SrcIdx < 0)
+ return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
+ if (SrcIdx < (int)LHSWidth)
Src = SVI->getOperand(0);
- else if (SrcIdx < LHSWidth*2) {
+ else {
SrcIdx -= LHSWidth;
Src = SVI->getOperand(1);
- } else {
- return ReplaceInstUsesWith(EI, UndefValue::get(EI.getType()));
}
+ Type *Int32Ty = Type::getInt32Ty(EI.getContext());
return ExtractElementInst::Create(Src,
- ConstantInt::get(Type::getInt32Ty(EI.getContext()),
+ ConstantInt::get(Int32Ty,
SrcIdx, false));
}
+ } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
+ // Canonicalize extractelement(cast) -> cast(extractelement)
+ // bitcasts can change the number of vector elements and they cost nothing
+ if (CI->hasOneUse() && EI.hasOneUse() &&
+ (CI->getOpcode() != Instruction::BitCast)) {
+ Value *EE = Builder->CreateExtractElement(CI->getOperand(0),
+ EI.getIndexOperand());
+ return CastInst::Create(CI->getOpcode(), EE, EI.getType());
+ }
}
- // FIXME: Canonicalize extractelement(bitcast) -> bitcast(extractelement)
}
return 0;
}
/// CollectSingleShuffleElements - If V is a shuffle of values that ONLY returns
-/// elements from either LHS or RHS, return the shuffle mask and true.
+/// elements from either LHS or RHS, return the shuffle mask and true.
/// Otherwise, return false.
static bool CollectSingleShuffleElements(Value *V, Value *LHS, Value *RHS,
std::vector<Constant*> &Mask) {
assert(V->getType() == LHS->getType() && V->getType() == RHS->getType() &&
"Invalid CollectSingleShuffleElements");
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
-
+
if (isa<UndefValue>(V)) {
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
return true;
}
-
+
if (V == LHS) {
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
return true;
}
-
+
if (V == RHS) {
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()),
i+NumElts));
return true;
}
-
+
if (InsertElementInst *IEI = dyn_cast<InsertElementInst>(V)) {
// If this is an insert of an extract from some other vector, include it.
Value *VecOp = IEI->getOperand(0);
Value *ScalarOp = IEI->getOperand(1);
Value *IdxOp = IEI->getOperand(2);
-
+
if (!isa<ConstantInt>(IdxOp))
return false;
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
+
if (isa<UndefValue>(ScalarOp)) { // inserting undef into vector.
// Okay, we can handle this if the vector we are insertinting into is
// transitively ok.
// If so, update the mask to reflect the inserted undef.
Mask[InsertedIdx] = UndefValue::get(Type::getInt32Ty(V->getContext()));
return true;
- }
+ }
} else if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)){
if (isa<ConstantInt>(EI->getOperand(1)) &&
EI->getOperand(0)->getType() == V->getType()) {
unsigned ExtractedIdx =
cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
-
+
// This must be extracting from either LHS or RHS.
if (EI->getOperand(0) == LHS || EI->getOperand(0) == RHS) {
// Okay, we can handle this if the vector we are insertinting into is
if (CollectSingleShuffleElements(VecOp, LHS, RHS, Mask)) {
// If so, update the mask to reflect the inserted value.
if (EI->getOperand(0) == LHS) {
- Mask[InsertedIdx % NumElts] =
+ Mask[InsertedIdx % NumElts] =
ConstantInt::get(Type::getInt32Ty(V->getContext()),
ExtractedIdx);
} else {
assert(EI->getOperand(0) == RHS);
- Mask[InsertedIdx % NumElts] =
+ Mask[InsertedIdx % NumElts] =
ConstantInt::get(Type::getInt32Ty(V->getContext()),
ExtractedIdx+NumElts);
-
}
return true;
}
}
}
// TODO: Handle shufflevector here!
-
+
return false;
}
/// that computes V and the LHS value of the shuffle.
static Value *CollectShuffleElements(Value *V, std::vector<Constant*> &Mask,
Value *&RHS) {
- assert(V->getType()->isVectorTy() &&
+ assert(V->getType()->isVectorTy() &&
(RHS == 0 || V->getType() == RHS->getType()) &&
"Invalid shuffle!");
unsigned NumElts = cast<VectorType>(V->getType())->getNumElements();
-
+
if (isa<UndefValue>(V)) {
Mask.assign(NumElts, UndefValue::get(Type::getInt32Ty(V->getContext())));
return V;
Value *VecOp = IEI->getOperand(0);
Value *ScalarOp = IEI->getOperand(1);
Value *IdxOp = IEI->getOperand(2);
-
+
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
EI->getOperand(0)->getType() == V->getType()) {
unsigned ExtractedIdx =
- cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
+
// Either the extracted from or inserted into vector must be RHSVec,
// otherwise we'd end up with a shuffle of three inputs.
if (EI->getOperand(0) == RHS || RHS == 0) {
RHS = EI->getOperand(0);
Value *V = CollectShuffleElements(VecOp, Mask, RHS);
- Mask[InsertedIdx % NumElts] =
- ConstantInt::get(Type::getInt32Ty(V->getContext()),
- NumElts+ExtractedIdx);
+ Mask[InsertedIdx % NumElts] =
+ ConstantInt::get(Type::getInt32Ty(V->getContext()),
+ NumElts+ExtractedIdx);
return V;
}
-
+
if (VecOp == RHS) {
Value *V = CollectShuffleElements(EI->getOperand(0), Mask, RHS);
// Everything but the extracted element is replaced with the RHS.
}
return V;
}
-
+
// If this insertelement is a chain that comes from exactly these two
// vectors, return the vector and the effective shuffle.
if (CollectSingleShuffleElements(IEI, EI->getOperand(0), RHS, Mask))
}
}
// TODO: Handle shufflevector here!
-
+
// Otherwise, can't do anything fancy. Return an identity vector.
for (unsigned i = 0; i != NumElts; ++i)
Mask.push_back(ConstantInt::get(Type::getInt32Ty(V->getContext()), i));
Value *VecOp = IE.getOperand(0);
Value *ScalarOp = IE.getOperand(1);
Value *IdxOp = IE.getOperand(2);
-
+
// Inserting an undef or into an undefined place, remove this.
if (isa<UndefValue>(ScalarOp) || isa<UndefValue>(IdxOp))
ReplaceInstUsesWith(IE, VecOp);
-
- // If the inserted element was extracted from some other vector, and if the
+
+ // If the inserted element was extracted from some other vector, and if the
// indexes are constant, try to turn this into a shufflevector operation.
if (ExtractElementInst *EI = dyn_cast<ExtractElementInst>(ScalarOp)) {
if (isa<ConstantInt>(EI->getOperand(1)) && isa<ConstantInt>(IdxOp) &&
EI->getOperand(0)->getType() == IE.getType()) {
unsigned NumVectorElts = IE.getType()->getNumElements();
unsigned ExtractedIdx =
- cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
+ cast<ConstantInt>(EI->getOperand(1))->getZExtValue();
unsigned InsertedIdx = cast<ConstantInt>(IdxOp)->getZExtValue();
-
+
if (ExtractedIdx >= NumVectorElts) // Out of range extract.
return ReplaceInstUsesWith(IE, VecOp);
-
+
if (InsertedIdx >= NumVectorElts) // Out of range insert.
return ReplaceInstUsesWith(IE, UndefValue::get(IE.getType()));
-
+
// If we are extracting a value from a vector, then inserting it right
// back into the same place, just use the input vector.
if (EI->getOperand(0) == VecOp && ExtractedIdx == InsertedIdx)
- return ReplaceInstUsesWith(IE, VecOp);
-
+ return ReplaceInstUsesWith(IE, VecOp);
+
// If this insertelement isn't used by some other insertelement, turn it
// (and any insertelements it points to), into one big shuffle.
if (!IE.hasOneUse() || !isa<InsertElementInst>(IE.use_back())) {
Value *LHS = CollectShuffleElements(&IE, Mask, RHS);
if (RHS == 0) RHS = UndefValue::get(LHS->getType());
// We now have a shuffle of LHS, RHS, Mask.
- return new ShuffleVectorInst(LHS, RHS,
- ConstantVector::get(Mask));
+ return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Mask));
}
}
}
-
+
unsigned VWidth = cast<VectorType>(VecOp->getType())->getNumElements();
APInt UndefElts(VWidth, 0);
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
- if (SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts))
+ if (Value *V = SimplifyDemandedVectorElts(&IE, AllOnesEltMask, UndefElts)) {
+ if (V != &IE)
+ return ReplaceInstUsesWith(IE, V);
return &IE;
-
+ }
+
return 0;
}
Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
Value *LHS = SVI.getOperand(0);
Value *RHS = SVI.getOperand(1);
- std::vector<unsigned> Mask = getShuffleMask(&SVI);
-
+ std::vector<int> Mask = getShuffleMask(&SVI);
+
bool MadeChange = false;
-
+
// Undefined shuffle mask -> undefined value.
if (isa<UndefValue>(SVI.getOperand(2)))
return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
-
- unsigned VWidth = Mask.size();
- unsigned LHSWidth = cast<VectorType>(LHS->getType())->getNumElements();
-
+
+ unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
+
+ if (VWidth != cast<VectorType>(LHS->getType())->getNumElements())
+ return 0;
+
APInt UndefElts(VWidth, 0);
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
- if (SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
+ if (Value *V = SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
+ if (V != &SVI)
+ return ReplaceInstUsesWith(SVI, V);
LHS = SVI.getOperand(0);
RHS = SVI.getOperand(1);
MadeChange = true;
}
-
+
// Canonicalize shuffle(x ,x,mask) -> shuffle(x, undef,mask')
// Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
if (LHS == RHS || isa<UndefValue>(LHS)) {
- if (isa<UndefValue>(LHS) && LHS == RHS)
- return ReplaceInstUsesWith(SVI, UndefValue::get(SVI.getType()));
-
+ if (isa<UndefValue>(LHS) && LHS == RHS) {
+ // shuffle(undef,undef,mask) -> undef.
+ return ReplaceInstUsesWith(SVI, LHS);
+ }
+
// Remap any references to RHS to use LHS.
std::vector<Constant*> Elts;
- for (unsigned i = 0, e = LHSWidth; i != VWidth; ++i) {
- if (Mask[i] >= 2*e)
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] < 0)
Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
else {
- if ((Mask[i] >= e && isa<UndefValue>(RHS)) ||
- (Mask[i] < e && isa<UndefValue>(LHS))) {
- Mask[i] = 2*e; // Turn into undef.
+ if ((Mask[i] >= (int)e && isa<UndefValue>(RHS)) ||
+ (Mask[i] < (int)e && isa<UndefValue>(LHS))) {
+ Mask[i] = -1; // Turn into undef.
Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
} else {
Mask[i] = Mask[i] % e; // Force to LHS.
RHS = SVI.getOperand(1);
MadeChange = true;
}
-
+
// Analyze the shuffle, are the LHS or RHS and identity shuffles?
- if (VWidth == LHSWidth) {
- bool isLHSID = true, isRHSID = true;
-
- for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
- if (Mask[i] >= e*2) continue; // Ignore undef values.
- // Is this an identity shuffle of the LHS value?
- isLHSID &= (Mask[i] == i);
-
- // Is this an identity shuffle of the RHS value?
- isRHSID &= (Mask[i]-e == i);
- }
-
- // Eliminate identity shuffles.
- if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
- if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
- }
-
- // Check for a handful of important shuffle(shuffle()) combinations.
- ShuffleVectorInst *LSVI = dyn_cast<ShuffleVectorInst>(LHS);
- if (!LSVI)
- return MadeChange ? &SVI : 0;
-
- LHS = LSVI->getOperand(0);
- std::vector<unsigned> LHSMask = getShuffleMask(LSVI);
- unsigned LHSInNElts = cast<VectorType>(LHS->getType())->getNumElements();
-
- // If the LHS is an identity shuffle, or if SVI + LHS form a full unpack
- // operation, merge the LHS and SVI shuffles. This allows llvm to emit
- // efficient code for matrix transposes written with generic vector ops.
- bool isLHSLoExtract = true, isLHSHiExtract = true;
- bool isUnpackLo = isPowerOf2_32(VWidth);
- bool isUnpackHi = isPowerOf2_32(VWidth);
- for (unsigned i = 0, e = LHSMask.size(); i != e; ++i) {
- if (LHSMask[i] >= LHSInNElts*2) continue; // Ignore undef values;
- isLHSLoExtract &= (LHSMask[i] == i);
- isLHSHiExtract &= (LHSMask[i] == i+(LHSInNElts/2));
- isUnpackLo &= (LHSMask[i] == (i/2));
- isUnpackHi &= (LHSMask[i] == (i/2) + (e/2));
- }
- for (unsigned i = 0, e = Mask.size(); i != e && (isUnpackLo || isUnpackHi);
- i += 2) {
- isUnpackLo &= (Mask[i] == i) && (Mask[i+1] == (i/2)+e);
- isUnpackHi &= (Mask[i] == i) && (Mask[i+1] == (i/2)+e+(e/2));
- }
- if ((isLHSLoExtract || isLHSHiExtract || isUnpackLo || isUnpackHi) &&
- (isa<UndefValue>(RHS) || (LHSWidth == LHSInNElts))) {
- std::vector<Constant*> Elts;
- for (unsigned i = 0, e = VWidth; i != e; ++i) {
- if (Mask[i] >= 2*LHSWidth)
- Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
- else if (Mask[i] >= e)
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
- Mask[i]));
- else
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
- LHSMask[Mask[i]]));
- }
- if (isa<UndefValue>(RHS))
- RHS = UndefValue::get(LHS->getType());
- return new ShuffleVectorInst(LHS, RHS, ConstantVector::get(Elts));
- }
+ bool isLHSID = true, isRHSID = true;
- // If rhs is shuffle + identity, propagate.
- if (ShuffleVectorInst *RSVI = dyn_cast<ShuffleVectorInst>(RHS)) {
- std::vector<unsigned> RHSMask = getShuffleMask(RSVI);
- unsigned RHSInNElts =
- cast<VectorType>(RSVI->getOperand(0)->getType())->getNumElements();
-
- // If rhs is identity, propagate
- bool isRHSLoExtract = true, isRHSHiExtract = true;
- for (unsigned i = 0, e = RHSMask.size(); i != e; ++i) {
- if (RHSMask[i] >= RHSInNElts*2) continue; // Ignore undef values;
- isRHSLoExtract &= (RHSMask[i] == i);
- isRHSHiExtract &= (RHSMask[i] == i+(RHSInNElts/2));
- }
- if ((isRHSLoExtract || isRHSHiExtract) && (LHSWidth == RHSInNElts)) {
- std::vector<Constant*> Elts;
- for (unsigned i = 0, e = VWidth; i != e; ++i) {
- if (Mask[i] >= 2*LHSWidth)
- Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
- else if (Mask[i] < LHSWidth)
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
- Mask[i]));
- else
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
- RHSMask[Mask[i]-LHSWidth]+LHSWidth));
- }
- SVI.setOperand(1, RSVI->getOperand(0));
- SVI.setOperand(2, ConstantVector::get(Elts));
- return &SVI;
- }
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ if (Mask[i] < 0) continue; // Ignore undef values.
+ // Is this an identity shuffle of the LHS value?
+ isLHSID &= (Mask[i] == (int)i);
+
+ // Is this an identity shuffle of the RHS value?
+ isRHSID &= (Mask[i]-e == i);
}
-
- // Be extremely conservative when merging shufflevector instructions. It is
- // difficult for the code generator to recognize a merged shuffle, which
- // usually leads to worse code from merging a shuffle.
- if (!isa<UndefValue>(RHS))
- return MadeChange ? &SVI : 0;
-
- // If the merged shuffle mask is one of the two input shuffle masks, which
- // just removes one instruction. This should handle splat(splat) -> splat.
- if (LHSMask.size() == Mask.size()) {
- std::vector<unsigned> NewMask;
- for (unsigned i = 0, e = Mask.size(); i != e; ++i)
- if (Mask[i] >= e)
- NewMask.push_back(2*e);
- else
- NewMask.push_back(LHSMask[Mask[i]]);
-
- // If the result mask is equal to the src shuffle or this shuffle mask,
- // do the replacement.
- if (NewMask == LHSMask || NewMask == Mask) {
- std::vector<Constant*> Elts;
- for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
- if (NewMask[i] >= LHSInNElts*2) {
- Elts.push_back(UndefValue::get(Type::getInt32Ty(SVI.getContext())));
- } else {
- Elts.push_back(ConstantInt::get(Type::getInt32Ty(SVI.getContext()),
- NewMask[i]));
+
+ // Eliminate identity shuffles.
+ if (isLHSID) return ReplaceInstUsesWith(SVI, LHS);
+ if (isRHSID) return ReplaceInstUsesWith(SVI, RHS);
+
+ // If the LHS is a shufflevector itself, see if we can combine it with this
+ // one without producing an unusual shuffle. Here we are really conservative:
+ // we are absolutely afraid of producing a shuffle mask not in the input
+ // program, because the code gen may not be smart enough to turn a merged
+ // shuffle into two specific shuffles: it may produce worse code. As such,
+ // we only merge two shuffles if the result is either a splat or one of the
+ // two input shuffle masks. In this case, merging the shuffles just removes
+ // one instruction, which we know is safe. This is good for things like
+ // turning: (splat(splat)) -> splat.
+ if (ShuffleVectorInst *LHSSVI = dyn_cast<ShuffleVectorInst>(LHS)) {
+ if (isa<UndefValue>(RHS)) {
+ std::vector<int> LHSMask = getShuffleMask(LHSSVI);
+
+ if (LHSMask.size() == Mask.size()) {
+ std::vector<int> NewMask;
+ bool isSplat = true;
+ int SplatElt = -1; // undef
+ for (unsigned i = 0, e = Mask.size(); i != e; ++i) {
+ int MaskElt;
+ if (Mask[i] < 0 || Mask[i] >= (int)e)
+ MaskElt = -1; // undef
+ else
+ MaskElt = LHSMask[Mask[i]];
+ // Check if this could still be a splat.
+ if (MaskElt >= 0) {
+ if (SplatElt >=0 && SplatElt != MaskElt)
+ isSplat = false;
+ SplatElt = MaskElt;
+ }
+ NewMask.push_back(MaskElt);
+ }
+
+ // If the result mask is equal to the src shuffle or this
+ // shuffle mask, do the replacement.
+ if (isSplat || NewMask == LHSMask || NewMask == Mask) {
+ std::vector<Constant*> Elts;
+ Type *Int32Ty = Type::getInt32Ty(SVI.getContext());
+ for (unsigned i = 0, e = NewMask.size(); i != e; ++i) {
+ if (NewMask[i] < 0) {
+ Elts.push_back(UndefValue::get(Int32Ty));
+ } else {
+ Elts.push_back(ConstantInt::get(Int32Ty, NewMask[i]));
+ }
+ }
+ return new ShuffleVectorInst(LHSSVI->getOperand(0),
+ LHSSVI->getOperand(1),
+ ConstantVector::get(Elts));
}
}
- return new ShuffleVectorInst(LHS, LSVI->getOperand(1),
- ConstantVector::get(Elts));
}
}
+
return MadeChange ? &SVI : 0;
}
projects / oota-llvm.git / blobdiff